APAs are currently available for use with a variety of display systems. Several of these APA printers are capable of printing both character and graphic images. A typical APA printer receives a dot-image associated with the image to be displayed from a processor which is then printed. The processor, in other words, is required not only to generate a vector list of the image to be displayed on, for example, a storage tube, but also to convert that vector list into a dot-image for transmission to the APA printer. No APA printer is available which can obtain the information to be printed directly from the display itself. In fact, no currently available APA printer can even attach to a storage tue. This inability to print directly from the display requires a user to have an image which was edited on a display to be routed back to the host processor to be stored. The host then must route this newly stored image to an APA printer to be printed. The time and expense associated with using a host in this manner, as well as the user's desire for the capability to create a real-time copy of the image displayed resulted in the development of the image copier.
Currently available image copiers are used with direct-view storage tubes (DVST) to make copies of the image displayed on the DVST directly from the DVST itself. The DVST, of course, is a highly desirable display because of its inherent capability to display highly complex and detailed images. Copying an image from a DVST is accomplished by the analog scanning of the DVST and passing this analog scan on to a DVST-like element within the image copier. This scanning is controlled by all analog circuits. These image copiers are relatively expensive to purchase and operate. They also typically employ a photographic process (i.e., the paper is pressed against the DVST-like element) and paper which has both limited life and stringent temperature storage requirements. Currently available image copiers are also very limited and inflexible from a functional standpoint: the image to be copied cannot be manipulated, scaled or enhanced prior to copying; overlaying images on top of one another is impossible; and an image cannot be copied without first being displayed on the DVST.